I'm in my early 60s and I'm still hanging in there, but it's a daily challenge.
I've been doing a lot of bodyweight exercises. A push up is a bodyweight exercise, but there are lots of others. I do an upper body routine one day, and a lower body the other, and then every 3 or 4 days I do a form of push up using a downward dog pose. I do 150 of those (not all at once).
There is a guy across the street who orders via Uber Eats (or whoever). I see him happily collecting his bag of food every day from his masked driver. Poor guy has put on about 60 pounds in six months.
So exercise, find a way to eat well, get out and walk. And remember, drinking is a young person's game. At some point, it's always best to just keep booze out of your system. It's actually pretty nasty stuff.
Oddly, even though I like to cook, I haven't been into it during this pandemic. So I find myself eating a TON of salads, a lot of it the premixed variety that comes in a bag.
The general rules of pandemic and pre-eating pandemic eating are the same for me, although the particulars have changed: Avoid processed stuff, avoid ingredients I can't pronounce, eat lots of veggies.
As for actually getting old, don't worry about it too much. It's better than the alternative.